215 



In a "normal" development, the contents of these nutritive 

 Bues a^-o devoured by the gall animals. Under ahnormal con- 

 ions, however, the nutritivo material of the plant cells 



X'^of^i^""^ ^T^^'.^^.'^f^J'. ^^^-^ °^ Peciiaspis Aceris (cynipides), 

 freed from their inhabitants and l ^ft in solutions which are 

 poor m food stuffs, or in ordinary tap wafer, remain alive for 

 weeks; but the contents of the nutritive tissues disappear. If 

 galls of a similar Irind, ceteris naribuw, are put in a sugar 

 soluoion, the contents of the nutritive tissues remain unused 

 or nay ovon be slightly increased. 



4. /^I^J''^-^-'- distinguish two forms of nutritive tissues: the 

 BBI£ltlI£-i^.PJ-^g.y nls and the nutritive prrenchyma , Nutritive 

 tissues of the first kind are present, when, for example, in 

 sac gjlls or walled galls, the space occupied by the gall ani- 

 mals is lined v/ith a clearly recognizable epidermis, vrhich func- 

 tions as nutritive tissue, Very often, delicate walled hairs, 

 Y? t/"'^^ oxtraordirR.rily rich in food stuffs, are produced on 

 it which we will term nutr itive hairs . We speak of nutritive 

 parenohTmr.. when the wefltfiiled cells belong to the ground tis- 

 sue. Thif. form of nutritive tissue plays a large part especi- 

 ajtly in medullary oulls. The nutritive parench^/ma usually con- 

 slFte of mt'.ny cell layers, which can differ greatly among them- 

 selves, in the quality of their contents. A double "nutritive 

 mantel" may be often developed, just as in mD.ny galls the larval 

 cavities are protected by a double mechanical mp-ntel. The in- 

 ner nutritive 7.one is then enclosed by the mechanical tissue and 

 belongs to the inner gall; the other lies outside the mechanical 

 mantel and belongs therefore to the gall bark. Conditions are 

 very complicated, when two mechanical and two nutritive mantels 

 are present. 



Nutritive Epidermis 



Me find a nutritive epidermis in imny leaf afio galls, v;hich 

 have been produced by Phytoptes and Aphides. The inner epider- 

 mis of the infected part of the leaf remains delicate, develops 

 only a thin cuticle and is usually richly filled with albumin- 

 ous stuffs. There is nothing unusual about the form of the cells, 

 so long as they do not grow out into hairs - nutritive hairs. 



We find papillae-like structures in the larval chamber of 

 the- gall of . Gecidomyia tJlmariae ; the cells are strongly curved 

 outward, their menbranes being often considerably thickened, 

 Nutritive hairs occur on the inner side of different mite galls 

 and in their simple form seem similar to certain Erinexun hairs 

 in size as well as amount of cell contents {compare figures 85a 

 and 113a). Alibuminous substances abound in their lumina, such 

 as drops of fat and also small grains of starch. Small papillae 

 (251) or flask-like hairs are found^on the galls of many Aphides (on 

 Poipulus Pemphigus spirothece )-^ on TJlmus Tetraneura compressa 

 (figure 113B} and many others. 



Nutritive Parenchyma 



It is evlddlnt that no sharp line moiy be drawn betv/een the 

 superficial nutritive tissues, which still bear distinctly the 

 character of the epidermis, and the inner grotmd tissue com- 

 plexes of the nutritive parenchjona, since many walled galls, 

 which, as we have seen, are lined with epidermis, can grow into 

 completely closed balls etc., the cells of the epidermis then 

 often undergoing the same development as the cells of the bor- 

 dering ground tissue layers. 



